This proposal is a multidisciplinary approach to examine the hypothesis that the initial AU alters the BAB permeability, setting up stages for recurrence. The basis of this application will be to evaluate the tight junctions of the BAB following an intravitreal injection of endotoxin. The applicant will then look at the BAB repair in both the ciliary epithelium and iris vascular endothelium at several levels. The applicant has past experience with these techniques, including in vivo aqueous fluorophotometry and tracer localization with EM, computational modeling of the protein kinetics and confocal and electron microscopy localization of molecular probes relevant to the junctional reassembly. Freeze fracture will also be conducted. The last specific aim will be to use high resolution contract MRI to determine if anterior diffusion pathways exists in normal humans.